1. Field of the Invention
This invention concerns portable moored systems for near real-time detection of tsunamis in the deep ocean environment. Measurement and reporting of tsunamis in the deep ocean with this invention provides data free from coastal effects that is essential for accurate forecasting of tsunami impacts and in time to evacuate coastal residential areas. Additional applications of this invention include tsunami model verification, satellite altimetry validation and calibration; seafloor inflation or deflation measurement, for example, subsea volcano monitoring or monitoring of subsea oil and gas fields.
2. Background
The mission of the Pacific Marine Environmental Laboratory (PMEL), Seattle, Wash., (www.pmel.noaa.gov) is to conduct interdisciplinary scientific investigations in oceanography and atmospheric science. The Laboratory's strength lies in the experience and knowledge of its scientific and engineering staff and their ability to obtain, process, analyze, and distribute high-quality oceanographic measurements. Current programs focus on open ocean observations in support of long-term monitoring and prediction of the ocean environment on time scales from seconds to decades. Studies are conducted to improve our understanding of the complex physical and geochemical processes operating in the world oceans, to define the forcing functions and the processes driving ocean circulation and the global climate system, and to improve environmental forecasting capabilities and other supporting services for marine commerce and fisheries. Results from PMEL research activities contribute to National Oceanic and Atmospheric Administration (NOAA) strategic goals of implementing seasonal-to-interannual climate forecasts, assessing and predicting decadal to centennial climate change, advancing short-term warning and forecast services, and building sustainable fisheries. Major programs include:                1. TAO Project—Real-time data from moored ocean buoys for improved detection, understanding and prediction of El Nino and La Nina.        2. FOCI Program—(Fisheries-Oceanography Coordinated Investigations)—a joint research program of NOAA's National Marine Fisheries Service to understand the recruitment of Walleye Pollock in the Gulf of Alaska and Bering Sea.        3. VENTS Program—Conducts research on the impacts and consequences of submarine volcanoes and hydrothermal venting on the global ocean.        4. Tsunami Program—seeks to mitigate tsunami hazards to Hawaii, California, Oregon, Washington and Alaska. Research and development activities focus on an integrated approach to improving tsunami warning and mitigation.        
The invention uses a tsunameter on the seafloor that precisely measures the pressure over time in the deep ocean. One application of a tsunameter is to measure ocean pressure for detecting the presence or absence of a tsunami. Just as seismometers have been essential to progress in the field of earthquake research, a tsunameter is critical to the further advancement of tsunami research and hazard mitigation and warning. NOAA-PMEL has developed a reliable tsunameter and successfully integrated that capability into a moored system now known as DART (Deep Ocean Assessment and Reporting of Tsunamis). An operational network, though currently small, has been established in the Pacific Ocean. DART is a powerful catalyst for the revolutionary paradigm shift now underway in tsunami research and forecasting—away from indirect observations and toward direct, high-quality measurements and analyses of the tsunami itself. Elements of the DART system can be deployed in several configurations. In stand-alone configuration, the tsunameter internally records pressure data on the seafloor for later analysis. In realtime configuration the tsunameter communicates to a surface buoy via an acoustic modem. The surface buoy then relays the data thru a satellite to shore station for near real time communications. The tsunameter could also be connected to a cable for realtime bi-directional communications.
Until now tsunami research and operational decisions of Tsunami Warning Centers have depended primarily on analyses of seismic information and coastal tide gage measurement. Though valuable, these data are essentially indirect and their interpretation is difficult. Seismic data interpretation involves poorly understood seismic/hydrodynamic coupling. Similarly, the interpretation of tide gage data is difficult because of the complex tsunami transformations induced by interaction with continental shelf, coastline, and harbor features. Furthermore, a tide gage may not survive the impact of the tsunami itself and, if it does survive, the data are not reported until after the tsunami strikes a coastal community.
Engineering advances at NOAA's PMEL have led to the development of a system that acquires and delivers direct tsunami measurements at deep ocean locations between the source and distant communities, and transmits these data in real time to tsunami warning centers and the Internet.